1. Field of the Invention
The present invention generally relates to the formation of dielectric materials in semiconductor integrated circuits and more particularly to an improved dielectric material and process for forming the same.
2. Description of the Related Art
Current integrated circuit processing technology, such as trench capacitor technology, utilizes thin films of oxidized silicon nitride as the node dielectric responsible for charge storage in the dynamic random access memory (DRAM) cell. As ground rules of the devices continue to shrink however, maintaining the minimum cell capacitance becomes increasingly difficult and to this point, has been achieved via a thinning of the node nitride. An alternative approach is to increase the dielectric constant (k) of the node material via the utilization of an alternative oxide with higher K (e.g. Ta2O5, Al2O3, ZrO2, BSTO, etc.). Although higher dielectric constants can be achieved, processing temperatures in excess of 1000xc2x0 C. are commonly required for such high k-trench capacitor DRAM""S. The elevated processing temperatures and extended soak times required at such temperatures commonly result in crystallization of the dielectric and excessive leakage along the resultant grain boundaries.
Therefore, there is a need for an improved dielectric that can be used with conventional semiconductor processing and that does not crystalize at processing temperatures in excess of 1000xc2x0 C. The invention discussed below presents such a dielectric.
In view of the foregoing and other problems, disadvantages, and drawbacks of the conventional dielectric materials, the present invention has been devised, and it is an object of the present invention to provide a structure and method for an improved dielectric material. In order to attain the object(s) suggested above, there is provided, according to one aspect of the invention a process of forming a dielectric in an integrated circuit structure that includes introducing precursors on a substrate, oxidizing the precursors and heating the precursors. The introducing and the oxidizing of the precursors is preformed in a manner so as to form an amorphous glass dielectric on the substrate. The process preferably includes, before introducing the precursors on the substrate, cleaning the substrate. The introducing of precursors is performed in molar ratios consistent with formation of glass films and may be achieved using ALCVD or MOCVD (i.e. Atomic layer CVD or Metal-organic CVD) of La2O3 and Al2O3 using ratios between 20%-50% La2O3 and 50%-80% Al2O3.
The invention produces a dielectric that remains amorphous up to at least 1000xc2x0 C. and that has a dielectric constant of approximately 20. Therefore, the dielectric produced with the invention remains amorphous at elevated temperatures and thus maintains low electrical leakage via the elimination of grain boundaries.